合成路线1

The hydrogenation of ethyl 3-(2-furyl)acrylate (I) with H2 over Raney-Ni in ethanol gives ethyl 3-(2-furyl)propionate (II), which oxidative methoxylation with Br2 in methanol affords ethyl 3-(2,5-dimethoxy-2,5-dihydro-2-furyl)propionate (III). The partial reduction of (III) with diisobutylaluminum hydride in toluene yields the substituted propionaldehyde (IV), which by a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide by means of NaH in DMSO gives 8-(2,5-dimethoxy-2,5-dihydro-2-furyl)-5-octenoic acid (VI). The hydrolytic ring opening of (VI), followed by an aldol cyclization in refluxing dioxane - water by means of sodium acetate - NaH2PO4 - hydroquinone affords 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoic acid (VII), which is isomerized by treatment with H2SO4 yielding 7-(5-oxo-3-hydroxycyclopenten-1-yl)-5-heptenoic acid (VIII). Methylation and esterification of (VIII) with H2SO4/refluxing methanol gives the methoxy methyl ester (IX), which by reaction with 2-mercaptoethanol (A) and sodium methoxide in methanol is converted into methyl 7-[5-oxo-3-(2-hydroxyethylthio)cyclopenten-1-yl]-5-heptenoate (X). The methylation of acid (VI) with NaH and methyl iodide gives the corresponding methyl ester (XIV), which is submitted to a hydrolytic ring opening and aldol cyclization as before to afford methyl 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoate (XV). The silylation of (XV) with trimethylchlorosilane and hexamethyldisilazane as usual yields the corresponding trimethylsilyloxy derivative (XVI), which is treated with 2-mercaptoethanol (A) and sodium methoxide to give the isomerized compound (X).